National Geographic

CREDITS HERE``````Satellite images let us see Earth fromabove. But a technology closer to Earthcan give us a much more detailed look.Aerial “light detection and ranging,”also known as lidar (rhymes with eye-dar), works by sending laser pulses froma plane, helicopter, or drone. The devicethen receives information back aboutthe surfaces below.In the past, the highest resolutionfor lidar was about 40 points per squareyard. But a team of researchers at NewYork University has increased the res-olution to 280 points per square yard,resulting in a view from above—espe-cially in urban areas—that’s far moredetailed than ever before and true tocracks, curbs, and building facades.What’s wrong with traditional imagesfrom space or miniature scale models?Lidar produces not just an image but ahigh-resolution geometric representa-tion of a city in motion. Slight slopes inpavement reveal how floodwater willmove, and pockets of particulates canidentify air pollution.“Let’s say you worked in public healthand you knew there was a high concen-tration of asthma in one neighborhood,”says NYU’s Debra Laefer, professor of ur-ban informatics. You could start lookingat corners where trucks idle, she says.Where is that pollution going? Can wechange the vegetation on the roof, thewater flow, which roads trucks use?Collecting data from the air isn’t cheap.But a lidar scanner can be affixed to craftthat fly for other purposes, such as po-lice or paramedic helicopters. The teamstarted with a scan of Dublin’s city center(pictured here). Future flights are possiblefor more cities—as is releasing the data tocity planners, businesspeople, and any-one else who might serve a community.``````BETTER THAN ABIRD’S-EYE VIEW``````By Daniel Stone``````HOW IT DIFFERSGoogle Earth renderings(like the one of Dublin atleft) use high-altitude imag-ery to create an approxima-tion of the surfaces below.Lidar, by comparison, cap-tures topography from muchlower and provides precisedata in space and time./,'$5,0$(ǖ&2/25,=('Ǘ%5,771(<2Å 1(,//$1''(%5$/$()(5&/28'&203$5((8523($15(6($5&+&281&,/6285&(66&5,336,167,787,212)2&($125$3+<12$$861$9<1$(%&